Zhen-Yuan Zhu

Polysaccharides from Lycium barbarum leaves: Isolation, characterization and splenocyte proliferation activity

The polysaccharides from the fruits of Lycium barbarum have received considerable attention in previous publication, but the polysaccharides from the leaves were rarely reported. In the present work, four water-soluble polysaccharide fractions: LBP-I, LBP-II, LBP-III and LBP-IV isolated from L. barbarum leaves were purified through DEAE-Sephadex A-25. LBP-II and LBP-IV respectively showed one symmetrical peak on HPGPC with average molecular weight of 9.39 × 10⁴ Da and 4.18 × 10⁵ Da. UV and IR analysis of the two fractions showed the characteristics of acidic polysaccharides combined with polypeptides or proteins. GC analysis showed LBP-IV was mainly composed of rhamnose, arabinose, xylose, glucose and galactose with molar ratio of 1.61:3.82:3.44:7.54:1.00, and the uronic acid content was 47.68% (w/w) determined by sulfuric acid-carbazole method. ¹H and ¹³C NMR spectra of LBP-IV also showed the presence of carboxyl carbon and five anomeric carbons, and suggested there may be both α- and β-anomeric configurations in this fraction. Moreover, splenocyte proliferation activity assay showed that LBP-IV significantly enhanced the proliferation of splenocyte stimulated by ConA or LPS, indicating the fraction has the beneficial effect on immunostimulating activity.

Structural properties of polysaccharides from cultivated fruit bodies and mycelium of Cordyceps militaris.

The structural properties of polysaccharides, respectively, obtained from the fermented mycelium and cultivated fruiting bodies of the Cordyceps militaris were investigated and compared in this paper. First, the crude polysaccharides were extracted from the mycelium and the fruiting bodies, respectively. The polysaccharides were successively purified by Sevag and chromatography on Sephadex G-100 column to produce two polysaccharides fractions termed CMPS-II and CBPS-II, respectively. The average molecular weights of CMPS-II and CBPS-II were 1.402×10(3) kDa and 1.273×10(3) kDa, respectively, and they were mainly composed of mannose, glucose and galactose in the mole ratios of 1:28.63:1.41 and 1:12.41:0.74, respectively, for CMPS-II and CBPS-II. Afterward, the structural features of CMPS-II and CBPS-II were investigated by a combination of chemical and instrumental analysis, such as FT-IR, periodate oxidation-Smith degradation, GC-MS, NMR and methylation analysis. The results indicated that structurally, both CMPS-II and CBPS-II were 1,3-branched-galactomannoglucan that had a linear backbone of (1→4)-linked α-D-glucopyranose (Glcp). Congo-red test revealed that CMPS-II and CBPS-II existed as triple-helical chains in 0.05-0.15 M NaOH solution.

Effects of extraction methods on the yield, chemical structure and anti-tumor activity of polysaccharides from Cordyceps gunnii mycelia

This study was to investigate the effects of different extraction methods on the yield, chemical structure and antitumor activity of polysaccharides from Cordyceps gunnii (C. gunnii) mycelia. Five extraction methods were used to extract crude polysaccharides (CPS), which include room-temperature water extraction (RWE), hot-water extraction (HWE), microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and cellulase-assisted extraction (CAE). Then Sephadex G-100 was used for purification of CPS. As a result, the antitumor activities of CPS and PPS on S180 cells were evaluated. Five CPS and purified polysaccharides (PPS) were obtained. The yield of CPS by microwave-assisted extraction (CPSMAE) was the highest and its anti-tumor activity was the best and its macromolecular polysaccharide (3000-1000kDa) ratio was the largest. The PPS had the same monosaccharide composition, but their obvious difference was in the antitumor activity and the physicochemical characteristics, such as intrinsic viscosity, specific rotation, scanning electron microscopy and circular dichroism spectra.

Sulfated modification of the polysaccharide from Cordyceps_gunnii mycelia and its biological activities

A chemically new sulfated polysaccharide (SPS50) was prepared from the water soluble polysaccharide (PS50), isolated from Cordyceps_gunnii mycelia, by concentrated sulfuric acid method. The yield of crude SPS50 was 62.34% and its specific rotation was [α](D)(20)=-36.75°. The structural characteristics of this chemically sulfated polysaccharide were determined based on the infrared analysis (IR), high performance liquid chromatography (HPLC) and sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE). Its biological properties including anti-oxidant and anti-tumor activities were also investigated. The results showed that the anti-oxidant capacity of SPS50 was not as good as SP50 and the anti-tumor activity of SPS50 was much better than PS50. SPS50 showed evident growth inhibition on K562 cells. The tumor inhibition ratio of SPS50 against K562 cells was 69.92%.

Synthesis and antitumor activity evaluation of chrysin derivatives

A series of 5,7-disubstituted chrysin, 7-monosubstituted chrysin, 5-monosubstituted chrysin derivatives were synthesized by alkylation, acetylation, benzoylation, carboxymethylation, and evaluated on their antitumor activity of H22 cells in the search for potential antitumor agents. Among them, compound 3 (5,7-diacetyl chrysin) displayed the most potent antitumor activity with IC50 value of 141 μM. Moreover, there is significant up-regulation of G2 in cell cycle of H22.

Mammalian elongation factor 4 regulates mitochondrial translation essential for spermatogenesis

Elongation factor 4 (EF4) is a key quality-control factor in translation. Despite its high conservation throughout evolution, EF4 deletion in various organisms has not yielded a distinct phenotype. Here we report that genetic ablation of mitochondrial EF4 (mtEF4) in mice causes testis-specific dysfunction in oxidative phosphorylation, leading to male infertility. Deletion of mtEF4 accelerated mitochondrial translation at the cost of producing unstable proteins. Somatic tissues overcame this defect by activating mechanistic (mammalian) target of rapamycin (mTOR), thereby increasing rates of cytoplasmic translation to match rates of mitochondrial translation. However, in spermatogenic cells, the mTOR pathway was downregulated as part of the developmental program, and the resulting inability to compensate for accelerated mitochondrial translation caused cell-cycle arrest and apoptosis. We detected the same phenotype and molecular defects in germline-specific mtEF4-knockout mice. Thus, our study demonstrates cross-talk between mtEF4-dependent quality control in mitochondria and cytoplasmic mTOR signaling.

Effect of ultrasonic treatment on structure and antitumor activity of mycelial polysaccharides from Cordyceps gunnii.

Taking mycelial polysaccharides from Cordyceps gunnii (C. gunnii) as the study subject, the effect of ultrasonic power, time and concentration of polysaccharides on antitumor activity of the polysaccharides was investigated. The ultrasonic processing condition of the polysaccharides was optimized by using orthogonal test design, and determined to be 400 W, 15 min and 1g/L. The change of structures of polysaccharides before and after ultrasonic treatment was also studied. Results show that ultrasonic treatment did not change the characteristic attribute of polysaccharides from C. gunnii. The composition of monosaccharide residues and the category of glycosidic bond have not been changed. But the molecular weight and intrinsic viscosity was reduced, and the alpha-helicity was enhanced after ultrasonic treatment. It was possible that ultrasonic treatment is an effective way for enhancing antitumor activity of polysaccharides.

Immunomodulatory effect of polysaccharides from submerged cultured Cordyceps gunnii

Context: The genus Cordyceps (Clavicipitaceae) is a group of entomopathogenic fungi that is widely used as tonic food or invigorant with broad-spectrum medicinal properties in China. Cordyceps gunnii (Berk.)Berk (C. gunnii), is also well known as the Chinese rare caterpillar fungus and has similar pharmacological activities with Cordyceps sinensis (C. sinensis). Polysaccharides (PS) from various Cordyceps species have demonstrated many interesting biological activities, including antitumor, immunopotentiation, hypoglycemic, and hypocholesterolemic activities. Objective: To investigate the effect of C. gunnii PS on the immunostimulatory antitumor function and expression of immune related cytokines in normal, immuno-suppressive, and H22-bearing mice, respectively. Methods: C. gunnii PS were extracted with hot water at 80°C for 2 h. Normal, immuno-suppressive, and H22-bearing mice were treated with PS respectively. By detecting the value of macrophage phagocytic index, proliferation of lymphocytes, natural killer (NK) cell activity and expression of related cytokines, interleukin (IL-4), tumor necrosis factor-α (TNF-a) and interferon-γ (IFN-γ), and tumor inhibition index in H22-bearing mice additionally, the effect of PS on immunostimulatory antitumor function and its mechanism were studied. Results: The total sugar content of the PS was determined to be 95% after purification. PS markedly increased the thymus and spleen indexes, the macrophage phagocytosis, the proliferation of splenic cells, and the level of IFN-γ and TNF-α. In tumor growth inhibition test, PS showed remarkable inhibition effects. Conclusion: PS from the C. gunnii could enhance nonspecific immunological function, humoral immunity, cellular immunity in mice, and inhibit tumor growth.

Synthesis, characterization and antioxidant activity of selenium polysaccharide from Cordyceps militaris.

A purified selenium-containing derivatives of Cordyceps militaris polysaccharide synthesized using H2SeO3/HNO3 and BaCl2 as a catalyst was investigated in this paper. The reaction condition was optimized by selecting different reaction temperature and period. Afterward, the one with the highest Se content was purified by ultra-filtration device with a molecular cut off size of 10KDa. Followed by its structural characterizations. Results of IFR and 13C NMR spectroscopy indicated that C-6 substitution was predominant in selenized polysaccharide. The modified polysaccharide with molecular weight of 1998 KDa was mainly consisted of mannose, glucose and galactose in the mole ratios of with the mole ratios of 1:28.63:1.41. Thermogravimetric and morphological analyses of the samples were carried out by AFS, SEM and AFM. In addition, the in vitro antioxidant results suggested that selenium-containing polysaccharide should be applied as a novel selenium source in dietary supplements, with potent antioxidant properties.

Structural characterization and inhibition on α-d-glucosidase activity of non-starch polysaccharides from Fagopyrum tartaricum

In the present study, the crude polysaccharide was extracted from Fagopyrum tartaricum and purified by Sephadex G-25 and G-75 column to produce a polysaccharide fraction termed TBP-II. Its average molecular weight was 26kDa. The structural characterization of TBP-II was investigated by gas chromatography, periodate oxidation-Smith degradation, Methylation and NMR. Congo red was applied to explore its advanced structures. The results revealed that chemical composition and structural characteristic of TBP-II was mainly consisted of galactose, arabinose, xylose and glucose with a molar ratio of 0.7:1:6.3:74.2. The backbone of TBP-II was composed of (1→4)-linked α-d-glucopyranosyl (Glcp), while the branches comprised of (1→3)-linked α-d-glucopyranosyl (Glcp), (1→6)-linked α-d-galactopyranosyl (Galp) and (1→2,4)-linked α-d-rhamnopyranosyl (Rhap). The structure of TBP-II was 1,3 and 1,6-branched-galactorhamnoglucan that had a linear backbone of (1→4)-linked α-d-glucopyranose (Glcp). Using Congo red assay showed that it was absent of triple helix structure. The α-d-glucosidase inhibitory activity of TBP-II was determined using acarbose as positive control. The result showed that the inhibition rate depended on the concentration of polysaccharides.